From DE 10 2005 007 745 A1, a longitudinal folding apparatus is known, wherein the folding table is equipped with a braking device, for example, a braking brush, on each side of the folding blade, for the purpose of preventing the product that will be folded from striking the stop at full speed. Instead, the product is to be decelerated in a specified manner via the braking device, and aligned in a specified manner at the stop. In this case, each braking brush is mounted on a support and is displaceable via actuators, wherein the two braking devices are connected in such a way that they can be moved away from the folding table together.
DE 694 00 629 T2 discloses a longitudinal folding apparatus comprising a folding blade and a stop that delimits the folding region on the folding table. Also provided is a brush braking device with brushes, wherein a servo unit is provided for adjusting the brush pressure of each brush or group of brushes. Two sensor systems spaced transversely to the product direction are provided, one on either side of the folding blade, with each such system on one side of the product path comprising a plurality of detectors, spaced in the direction of transport by 1 mm, for example, and each such system on the other side of the product path comprising an infrared source that illuminates the respective sensor system. The measuring range for these sensor systems extends over the stop and a region lying upstream thereof on the product side. By analyzing the degree of coverage and a distance from the stop, and optionally the temporal sequence of coverage in the folding process, a potentially flawed braking effect can be identified and automatically corrected. A comparison of the distance between stop and product edge over the degree of coverage of the two sensor systems makes it possible to monitor the leading edge with respect to a skewed or improper alignment. Using a control apparatus that contains the sensor systems, the effect of the braking device is adjusted on the basis of the reading from the sensor device such that the folding blade acts on every product that is optimally aligned in the folding region, wherein the leading edge comes to rest at the end face of the stop in such a way that the printed product is not damaged and is folded precisely. In this, the folding blade moves in phase displacement relative to the forward movement of the printed product, and therefore, it moves downward so as to engage with the upper side of each printed product when said product is entirely within the folding region, wherein the leading edge comes to rest directly at or very close to the end face of the stop. It is also observed in DE 694 00 629 T2 that for folding apparatuses in which the braking effect is achieved solely by the folding blade, the braking effect can be regulated by modifying the phase timing of the folding movement thereof.
From EP 2 017 210 A2, a longitudinal folding apparatus and a method for operating the longitudinal folding apparatus are known, wherein two speeds are determined by means of two detector systems, one in front of the other in the direction of transport, and the product to be folded longitudinally is decelerated from the first speed to the second speed via frictional contact exerted on the printed product, for example, via the folding blade, as the printed product moves along a braking path on the folding table. The time for starting the frictional contact that decelerates the printed product, for example, the first contact of the folding blade, is adjusted on the basis of a deviation of a determined actual value for the second speed of the printed product from a predetermined target value for this second speed. The goal in this is to ensure that the product will strike the stop for the braking and alignment of said product.
DE 198 56 373 A1 relates to an early warning system and a method for detecting jams of imprinted signatures. For this purpose, sets of sensors are provided downstream of the cross cutter of the cross folding apparatus, each upstream of two longitudinal folding apparatuses. When a skewed position is detected, an error message is sent out and the printing press is slowed or stopped.
From DE 100 63 528 A1, a method and a device for determining the accuracy of a folding position is disclosed, wherein markings imprinted onto the shingle flow are detected in the product output, and the position of said markings relative to the fold spine allows a conclusion to be drawn regarding fold quality. This can then be used by the operator as a tool for diagnosing defects, and also allows feedback on folding accuracy to be sent to the folding apparatus. When errors occur, such as skewed folds or overhanging paper, measures can be introduced for increasing folding accuracy, such as correcting a phase position of folding blade to folding jaw, regulating a speed of the transport element that transports the flow of shingles, or even shutting off the printing press, for example.
In DE 10 2004 058 647 A1, a buckle folding machine having a sensor is disclosed, wherein the sensor, or two sensors spaced transversely to the direction of conveyance, characterize the process for the incidence of the leading edge of a workpiece. The sensor or sensors can be embodied as a microphone, as an acceleration sensor, as strain gauges, or as ultrasonic sensors. In the latter case, the concept is to allow orientation signals to be generated that characterize the orientation of a leading edge being moved toward the pocket stop. Positioning means for adjusting the orientation of the pocket stop are actuated on the basis of the measured values from the sensor or sensors.
DE 32 34 148 A1 relates to a method and a device for inspecting folded sheets for deviations of the fold line from the target fold line on the basis of the type area in buckle or blade folding apparatuses. For this purpose, two sensors are provided in the flow of folded products, spaced transversely to the flow, and detect the distances between fold marks applied to the product and the fold edge, wherein an analysis unit uses this information to calculate and/or display a mean value deviation from the target value for longitudinal and angular deviations in the fold, and/or to utilize said deviation for the purpose of controlling the machine. This enables a selective correction of adjusted machine values.
From DE 199 50 603 B4, an infeed of sheets that are to be imprinted into a printing couple of a sheet-fed printing press is disclosed, wherein, by means of two ultrasonic sensors spaced transversely to the flow, information about the position of an individual sheet to be fed into the printing couple is provided before said sheet is fed by a gripper to the printing couple. In this manner, a skewed position or an undesirable double layer can be detected, which is coupled to a control and regulating device that is connected to the gripper.
EP 0 161 988 A1 proposes a longitudinal folding apparatus, in which only one sensor is provided, directly at the stop. The products entering on the folding table are controlled by adjusting the phase between product and folding blade contact, such that the product reaches the stop in a straight alignment. This is achieved by means of a relay circuit. If the products do not reach the sensor, the phase of the blade is adjusted to a later time, until the products are visible at the sensor. If the machine speed is increased by a control command input by the press operator, pressing the switch will also actuate a relay at the same time, so as to shift the point of contact of the blade to an earlier time. However, afterward the above-described automatic system re-engages, which again shifts the time point back until the sensor again “sees” the product. This procedure is intended to improve a prior art, which operates in a “floating” manner with two sensors, wherein one sensor is used for increasing the forward movement and the other is used for decreasing the forward movement.
From EP 0 462 421 A1, a method and a device for controlling the movement of the longitudinal folding blade are known, wherein at the stop, an acceleration sensor is disposed, which senses the accelerations of the incoming product. If the measured acceleration deviates from a target value, the folding time is adjusted. If the acceleration value detected by the sensor is too great, the folding time is shifted forward, and if it is too small, it is shifted backward.
DE 195 04 769 A1 relates to a longitudinal folding apparatus, wherein first sensors are provided at the front side of the stop, which sensors measure the distance of the leading edge as the product to be folded is conveyed thereto, and a control circuit analyzes, via comparison, whether the two halves are approaching at the same speed. If one side approaches the stop more quickly, the braking assembly assigned to this side will be brought closer to the folding table, in order to brake this side with greater force. Additional sensors are provided for measuring undulations in the folded copy. When embodied as optical sensors, these sensors that measure undulation can detect the distance from the upper side of the product, or, as strain gauges, they can measure the force exerted on them by the deformation of the upper side. If a maximum value is exceeded, the position of the braking devices is adjusted. In a further embodiment, additional sensors can be provided at the stop, by means of which a deformation of the leading edge can be detectable. In one embodiment, the stops can also be embodied as circular arches, or as rotatable about fulcra. The measured deformations are also to be suitable as control or regulating variables, for controlling and/or regulating the movement of the folding blade.